[Ichthyology • 2017] Gymnotocinclus canoeiro • A New Species of Gymnotocinclus from the rio Tocantins Basin with Phylogenetic Analysis of the Subfamily Hypoptopomatinae (Siluriformes: Loricariidae)

Gymnotocinclus canoeiro n. sp. of the Hypoptopomatinae is described from small tributaries of the upper rio Tocantins basin. It is distinguished from G. anosteos by having five characters: (1) the presence of body dermal plates, (2) the pectoral girdle not exposed in ventral view, (3) the pelvic spine longer than pectoral spine in males, (4) the pectoral fin with seven to eight branched rays, and (5) the presence of an adipose fin. Furthermore, maximum likelihood (ML) analysis was used to estimate a molecular phylogeny from previously published data of one nuclear (F-Reticulon 4) and three mitochondrial (16S RNA, COI and CytB) genes. The phylogenetic results revealed the new species as a sister taxon of Gymnotocinclus anosteos within the Otothyrini. We also included samples of Nannoplecostomus eleonorae that appeared sister group to all other Neoplecostomini species, and Plesioptopoma curvidens that appeared within the Neoplecostomini forming a sister clade to all species of Neoplecostomus, except N. ribeirensis and the species of Pareiorhina, except P. rudolphi.

Etymology. The specific name “canoeiro” is from Portuguese language for those person or people who handle and/or build canoes. The name is a reference to the indigenous people Avá-Canoeiro, a once numerous and powerful indigenous people inhabiting the upper rio Tocantins valley. The Avá-Canoeiro are now restricted to some small villages due to a series of gradual and abrupt murders, diseases, and the lack of legal hunting territories (Pequeno, 2005). Recently, the Avá-Canoeiro were known as the invisible people due to the fact that some of the few survivors used to live for more than a decade in caves to avoid contact with civilization, just leaving the caves at night to collect and chase food.

Distribution.Gymnotocinclus canoeiro is known from a single locality of a small tributary of the rio das Almas, which flows to the rio Paranã, rio Tocantins basin, Brazil (Fig. 7).

Ecological notes. The new species Gymnotocinclus canoeiro is found in a shallow and small clear water river, with rocky outcrops forming small waterfalls and substrates of rocks and sand,. In several portions of the stream where the new species was found, the marginal vegetation was well preserved, and due to the large trees there is poor light penetration. The species was found at the bottom of the river associated with substrates of rocks and wood.